The genetic changes mean that antibodies directed against Sars-CoV-2 neutralize the variants of the virus more poorly. This has implications for antibody therapies. However, it is unclear whether the mutations also render vaccines ineffective.
The news from Denmark sets off some alarm bells. The Danish Serum Institute reports that a new variant of Sars-CoV-2 has formed in mink, which has already infected more than 200 people and is apparently able to escape parts of the human immune response. The Danish government now fears that a possibly more dangerous variant of SARS-CoV-2 is spreading from Denmark, against which vaccines currently being tested may even be less effective. A partial blockade was imposed on the seven affected regions in North Jutland on Friday.
Information on the new mink variant was still too little to really assess the danger, explained Marion Koopmans of the Erasmus University of Rotterdam on request. Neither the transmission from mink to humans nor the fact that new coronaviruses change genetically in mink is surprising. This has already been demonstrated by Koopmans’ team after Dutch farm minks first contracted Sars-CoV-2 in late April. However, according to Koopmans, there has been no evidence to date that any of these new virus variants are more dangerous to humans.
According to a communication from the Serum Institute, the new variant in Denmark already shows four genetic changes (mutations) and also an important protein. It is the so-called Sars-CoV-2 spike protein, or the sting with which the virus attaches itself to the receptors of various human cells and then infects them.
It is not yet known whether the new mink variant therefore binds better to cells, reproduces faster, or harms human cells more. What is known and alarming, however, is the information from the Serum Institute that antibodies from patients with Covid-19 that block binding of the spike protein to the ACE receptor on the surface of human cells do so only to a limited extent with the new variant. mink. The antibodies apparently no longer correctly recognize the mutated form. This could mean that a person who had already been infected with another variant of Sars-CoV-2 would have poorer antibody protection against a second infection with the mink variant.
Antibody therapies currently under development – which Donald Trump also received, for example – also need to be reconsidered. This is also demonstrated by an international study published on Thursday and not yet reviewed. According to the study, the Danish mink variant is by no means the only variant of Sars-CoV-2 that is insensitive to some human antibodies. A variant called N439K has already appeared in twelve countries and is widespread in some cases. In cell culture studies, the neutralization of several antibodies was reduced by more than a factor of two compared to the original variant. It is also concerning that N439K viruses bind better to human cells in cell culture and multiply somewhat faster.
The N439K variant is not yet an acute threat, but according to the information available so far it is a little more threatening than the mink variant from Denmark. In any case, different antibodies directed against different areas of the spike protein should always be contained in a therapeutic cocktail, require researchers led by Glasgow’s David Robertson. So you have weapons against different virus variants.
It is not yet clear what this means for vaccine development. The Danish government fears that the vaccines currently being tested could be less effective if the mink variant spreads and then dominates a country or even a continent. Experts believe this is by no means proven. Because during a vaccination, the body’s immune system usually forms a whole group of antibodies in some kind of predictive prophylaxis, which are directed against different attachment points of the vaccine virus. As a rule, this means that at least some of the mutated viruses are recognized and neutralized. Furthermore, after a vaccination, our immune system forms a second army, namely T cells, which are specifically directed against a virus.
The killing of all minks, which Denmark has now ordered, is still a reasonable preventative measure. Because due to poor farming conditions, coronaviruses can spread rapidly on mink farms. Therefore it cannot be excluded that at some point mutations that are dangerous even for humans will arise. The Netherlands therefore decided weeks ago to close all mink farms by spring 2021. It remains to be seen if and when other countries with such companies, such as Poland, Finland, Spain, the United States or China, will follow suit.